My question is whether the brakes release AS SOON AS the clutch bites, or if you always have to wait the full 2 seconds after taking your foot off the brake.

My 2009 BMW 128i behaves the first way, as did the 1997 Subaru Impreza I had for a while a few years ago. Intuitively, this seems like how it should work, and after 25 years of driving other manual cars without it, it never gave me cause to think in either car.

The other way seems stupid, as (a) it makes you wait, and (b) you're STILL going to have to sit there with the clutch biting (and therefore wearing out) otherwise you're still going to roll back when the brakes DO come off!

I've found posts on the Chevy Sonic forums which apparently has the same system, but they're not clear on this point either.